Switch



Aug. 18, 1931. p cHAPLIN 1,819,675

SWITCH Filed May 4 1929 M CHAPL/N ATTORNEY Patented Aug. 13, 1931 UNITEDSTATES PATENT osnca IERLE P. OHAPLIN, OF WATERVILLE, MAINE, ASSIGNOR T0BELL TELEPHOR'R LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., ACORPORATION 01' NEW YORK swrrcn Application filed Kay 4,

This invention relates to automatic switches and particularly to theterminal banks for automatic switches employed in telephone systems.

The object of the invention is to improve the construction of switchterminal banks and to reduce the probability of faulty operation due towear or to manufacturing variations.

Heretofore, terminalbanks have been used, in which the terminals areconstructed with their sides converging to a central point to givegreater strength and durability to the bank structure. This isparticularly desirable when the terminals have to be placed closelytogether and consequently the tips of the terminals and the spacebetween them has to be small. I

According to this invention, the terminals are constructed with radialsides and are so arranged in a bank that thesides of adjacent terminalsare parallel. This is in order to permit greater manufacturing limits inthe construction of the switches in which the banks are used. With bankterminals arranged in this manner, brushes traveling over the terminalsurfaces will always encounter equal spacings between the terminals,even though the brushes may, for example, be slightly off-center, lessaccurately manufactured, or worn, which may cause them to engage theterminals further away or closer to the center of the switch. Bridgingbetween adjacent terminals is therefore avoided regardless of suchinaccuracies.

This invention has been illustrated in the accompanying drawings inwhich:

Fig. 1 shows a plan view of a terminal bank arranged in accordance withthis invention;

Fig. 2 shows a side view and cross-section of the bank shown in Fig. 1taken on a line 22 thereof;

Fig. 3 shows a fragmentary cross-section of two adjacent layers ofterminals, their separating plates and side views of portions ofcorresponding trunks;

Fig. 4 shows a plan view of one of the terminals; and

Fig. 5 shows an enlarged fragmentary plan view of two of the terminalsarranged in 1929. Serial No. 860,432.

a bank with the tip of the usual brush for making contact therewith.

- Fig. 6 shows an enlarged fragmentary front view of the brush andterminals shown in Fig. 5.

In Figs. 1 and 2 are shown layers of terminals 4 constructed inaccordance with this invention arranged in a semicircle with tenterminals in each layer and with the center lines of the terminalsconverging to the center point. Every two layers of terminals areseparated by a sheet of insulating material 5 which has its innersemicircular edge extending beyond the tips of the terminals of the twolayers. semicircular sheets of insulating material6 and 7 are placed onthe upper V and lower sides, respectively, of each pair of terminals asshown most clearly in Fig. 3.

Each two layers of. terminals with their in sulation plates 5, 6 and 7are separated by metal plates 8 and ten groups of suchlayers arearranged in this bank. This structure is held together by means of a topplate 10 and a bottom plate 11 and five bolts 13. The bolts 'areinserted through holes in the plates 10 and 11, the insulation sheets 5,6 and 7 and plates'8 and held in place by nuts 14.

The individual terminals 4 are cut as shown in Fig. 4 with the oppositeedges or sides of the contact portion 15 converging symmetricallytowards the tip of this portion. Themiddle portion 18 of the terminal 4has its opposite edges practically parallel, while the end portion 17 ofthe terminal is bent to one side and arranged for receiving solderedconnections to conductors. The alternate layers of the terminals 4 havetheir end portions 17 bent in opposite directions to evenly distributethese ends over the space available on the outer surface of the bank forsoldering of the conductors.

Referring now particularly to Figs. 3, 5 and 6, in Fig. 3 is shownportions of brushes 25 and 26 contacting with opposite terminals toindicate how the tips of these brushes engage the terminals. In Figs. 5and 6 the contact portions 15 of the terminals 4 and 4" are shown soarranged in the bank that their respectively adjacent edges 22 and 23are located in parallel relation to each other. Be-

tween these edges is shown the brush 25 which has its contact tip 27bent in a semicircular shape as shown most clearly in Fig. This tip 27when placed between the terminals will not touch the edges 22 and 23 butrest between the terminals on the insulation plate 5. When the brush ismoved by suitable switching means in the usual manner the tip 27 willslide up on the terminal 4 or 4" depending on the direction in which itis moved. The brush 25 should be so located that when it is moved overthe terminals its center line should coincide with the .center lines ofthe terminals and hence rotate on the axis passing through the centerpoint to which the center lines of the terminals converge. It will benoted from these enlarged views that even though the brush 25 may beless accurately manufactured or mounted so as to be slightly ofi center,the tip 27 will engage the terminals for approximately equal eriods oftime during the rotation of the brush over succeeding contact surfacesregardless of the points of the edges 22 or 23 of the terminals at whichthe tip leaves or engages the terminals. For example, if the brush 25 ofone switch structure should be slightly shorter than the brush ofanother, it would simply mean that in the former case the tip 27 wouldengage and leave the edges of the terminals further down towards the endof the tip portions 15 than in the latter case. As the distance betweenthe edges 22 and 23 will always remain the same no harm would resultfrom this inaccuracy in the manufacture of the brushes. In other wordsthe relative portions of time that the tips 26 would engage the contactsurfaces of the terminals would remain the same in both switchstructures. Such results could not be obtained in cases where, forexample, the sides of the individual terminals are parallel. In suchcases, if the brush of one switch were shorter than that of another, theperiods of contact between the brush and the terminals in the formercase would be longer than the periods of contact between the brush andthe terminals in the latter case. It might even happen that the shorterbrush when passing from one terminal to the other would bridge theseadjacent terminals. This tendency of bridging is even more likely tooccur when the contact tip surfaces of the brushes increase as thebrushes become worn. These tendencies of changes in contacting periodsand bridging of adjacent terminals are practically eliminated by havingthe adjacent sides of adjacent terminals parallel.

While a particular form of terminal has been shown as applied in thesingle type of switch bank, it is evident that terminals may bedifferently formed and arranged in many other bank structures withoutdeparting from the spirit of the invention, which should be limitedmerely by the scope of the appended claims. I

What is claimed is:

1. A curved terminal bank in which sides of adjacent terminals areparallel.

2. A terminal bank for rotary switches comprising terminals havingradial sides and arranged in the bank with the adjacent sides ofterminals parallel.

3. A terminal bank comprising terminals so shaped and so arranged in thebank that the adjacent sides of terminals are parallel and the centerlines of the terminals converge to a common oint.

4. A terminal ban com rising flat terminals arranged in semicircu inlayers so that the side of one terminal in a layer is parallel to theadjacent side of the adjacent terminal in said layer.

5. A semicircular terminal bank having terminals so formed that thespace between two terminals is of the same width as measured nearer orfurther away from the center of the semicircular bank.

6. A switch comprising a curved terminal bank of layers of terminals,the terminals in each layer being'arranged so that adjacent sides ofadjacent terminals are parallel, and a set of contact brushes arrangedwith one brush for each layer.

7. A terminal bank comprising terminals arranged with the center linesof the terminals converging to a central point and .the sides ofeachterminal converging to another point on its center line and furtherarranged so that one side of a terminal is parallel with the adjacentside of another terminal nearest to this side and that the other side ofsaid first mentioned terminal is parallel with the adjacent side ofanother terminal nearest to this other side of said first mentionedterminal.

In witness whereof, I hereunto subscribe my name this 30th day of April,1929.

MERLE P. CHAPLIN.

